Stretchable adjustable book marker



FIG. 1 is a front elevational view of the stretchable adjustable book marker showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is a reduced scale top perspective view thereof, shown with a book, the broken lines being for illustrative purposes only, forming no part of the claimed design. 

The ornamental design for a stretchable adjustable book marker, as shown and described. 